The invention relates to a fuel injection nozzle for internal combustion engines provided with a valve needle which opens against a closing force and with a control piston that acts on the valve needle and is acted upon by a fluid, especially fuel of varying pressure. In a known fuel injection nozzle of this type, the control piston is acted upon by a pressure that is basically the same as the pressure of the fuel coming from the fuel injection pump into the pressure chamber of the fuel injection nozzle. The diameter of the adjusting piston must therefore be relatively small, in any case smaller than that of the valve needle, and in addition, there must be a very good seal between this control piston and the bore that contains the same because of the high pressure involved. If an influence is to then be taken from other engine characteristic values for this pressure, then this pressure must be relatively high if it is to have a corresponding effect. A higher pressure, however, requires a relatively expensive pressure producer, together with all of the disadvantages associated with this type of high pressure device, such as, for example, (1) the great effect of even minor leakage on the pressure, (2) especially good sealing devices which are also necessary for safety reasons, and not least significant, (3) a difficult regulation of this relatively high pressure in dependence on engine characteristic values. A further disadvantage of this pressure that changes synchronously with the injection pressure is that a major problem of synchronization exists because of fluctuations in the pressure at the individual engine nozzles caused by valves and other devices, such as throttles, lines and leakage, etc. In a different known fuel injection nozzle the fuel that flows between the valve needle and the nozzle body acts on the control piston, so that this pressure is continually regulated by means of a pressure control valve. As mentioned above, this fuel injection nozzle has the same disadvantages as the other.